Yield and Nutrient Concentration Response to Switchgrass Biomass Harvest Date

Abstract

Timing of biomass removal from stands of switchgrass (Panicum virgatum L.) impacts the nutrient content of harvested material and fertilizer requirements for subsequent growing seasons. is study was conducted to determine the change in N, P, and K content of harvested switchgrass biomass as a function of the harvest date and to determine the economic consequences of an extended harvest window. Data were produced in a randomized complete block study conducted at the Oklahoma Agricultural Experiment Station, Stillwater, with six replications over three harvest seasons from November of 2007 to March of 2010. Treatments on the established stand of cultivar Kanlow consisted of ve harvest dates separated by about 30 d beginning in late November. Regression equations were used to t yield and N, P, and K concentration response to the harvest date. Delaying harvest beyond December resulted in an average 5.4% decline in harvested biomass per month. Delaying harvest beyond November did not result in a signi cant change in the N concentration in the harvested biomass. However, delaying harvest did result in a signi cant decrease in both P and K content in the harvested biomass. Point estimates from the response functions were used to estimate production cost for each of ve harvest dates beginning with 30 November and ending with 30 March. e quantities of P 2 O 5 and K 2 O fertilizer that would be required to replace the P and K removed with the biomass were used in the budgets. Biomass production cost was similar across harvest dates.

Switchgrass Harvest Time Effects on Nutrient Use and Yield: An Economic Analysis

“…Amounts of N, P, and K removed per acre decreased significantly with delayed harvest, which is consistent with nutrient translocation to the root system late in the production season (Parrish and Fike, 2005). Note that delayed harvest does not always lead to a statistically significant reduction in N concentration in the literature (Gouzaye et al, 2014;Guretzky et al, 2011). Haskell results, where only poultry litter was applied, showed lower N and K removal Yield was a major determinant of N and K removal, but not of P removal.…”

“…First frost signals the onset of switchgrass senescence, when the plant goes dormant and mobile nutrients are translocated to plant roots and crown (Parrish and Fike, 2005). Hence, delaying harvest dates past yield maximum results in lower biomass yield along with lesser nutrient removal (Adler et al, 2006;Gouzaye et al, 2014;Parrish and Fike, 2005).…”

Distribution of switchgrass (Panicum virgatum L.) aboveground biomass in response to nitrogen addition and across harvest dates

“…Management of perennial bioenergy cropping systems will dictate many of the agronomic, ecological and economic trade-offs that exist among management scenarios. Some authors report an economic advantage to harvest as close to senescence as possible [16], and others conclude that the cost of delaying harvest to spring is offset by the savings in P and K fertilizers (and no change in N fertilizer savings) [34]. However, nutrient conservation may not always be economically valuable to a farmer depending on fertilizer prices.…”

“…However, trade-offs among yield, crop quality, and environmental cost or benefit are inherent in decisions about the timing of switchgrass harvest, with economic and environmental implications. Although delaying harvest maximizes nutrient retranslocation, delays also reduce yield [24,[30][31][32][33][34][35] and can result in significant economic loss for farmers [16].…”

Reed canarygrass crop biomass and silage as affected by harvest date and nitrogen fertilization

“…Delaying harvest of perennial herbaceous species is seen as an option to reduce the mineral composition and minimize the risks of problems with direct combustion (Adler et al 2006;Hoagland et al 2013;Sadeghpour et al 2014: Gouzaye et al 2014. Wrobel et al (2009) suggest that the ideal harvest time for reed canarygrass used for ethanol production is at an advanced stage of development.…”